So confused

Hey ladies so about two weeks ago I took a pregnancy test and it looked positive. I then took at least 4 more and they all said the same thing. I had an appointment at my OBGYN and the night before i took another test just because and again positive. I go to my appointment and they did an ultrasound but there was no sign of a pregnancy. They did blood test and everything came back negative for pregnancy. They said to test in another week. So I tested this morning and there was a blue line indicating a positive result. But the line did not appear at first. Is this a positive result line or is this an evap line? I’m just so confused lol